The present invention relates to a photographic film cassette and, more particularly, to an improved photographic film cassette in which the rotation of the core of a spool causes a photographic film leader to advance to the outside of the cassette shell.
A known photographic film cassette includes a photographic filmstrip positioned so that a photographic film leader does not protrude from a cassette shell prior to loading the cassette into a camera. Such a cassette is easily loaded into the camera. Simple film-advancing mechanisms of the camera are used with this type of cassette and include a construction which rotates the core of a spool to unwind the filmstrip, thereby causing the leader to move through a photographic film passageway and protrude from the cassette. In this construction, a roll of the filmstrip wound about the core is prevented from loosening in order to transmit rotation of the core to the leader. A cassette disclosed in U.S. Pat. Nos. 4,834,306 and 4,848,693 has a spool provided with such disks or flanges on both lateral sides of the roll that circumferential lips are formed on the periphery of the flanges to project in the direction along the length of the cassette. Spreaders or guide projections are formed on the inside of the cassette shell in the positions between the film passageway and a photographic film chamber of the cassette shell for deforming the flanges outwardly to widen the interval between the flanges. The spreaders constantly spread the flanges so as to release the outermost turn of the roll from contact with the circumferential lips.
In order to produce the core and the flanges, using resin is very favorable since it is convenient and inexpensive. Due to deformation of the flanges, it is necessary for ensuring an unfailing advancement of the leader, with only a small torque applied to the core, to construct the flanges and the circumferential lips with a small thickness, e.g., 0.4 mm or below.
Such resinous flanges which are formed so as to have a small thickness for use in the cassettes are disadvantageous in that they exhibit low moldability and low efficiency during mass production, because the resin suitable for the present purposes has a high intensity and thus low flowability. To mold such flanges having a small thickness but a high intensity from resin according to injection molding, the cost for manufacturing the cassettes becomes too high.